Methods of utilizing block copolymer to form patterns

ABSTRACT

Some embodiments include methods of forming patterns in which a block copolymer-containing composition is formed over a substrate, and is then patterned to form a first mask. The block copolymer of the composition is subsequently induced into forming a repeating pattern within the first mask. Portions of the repeating pattern are then removed to form a second mask from the first mask. The patterning of the block copolymer-containing composition may utilize photolithography. Alternatively, the substrate may have regions which wet differently relative to one another with respect to the block copolymer-containing composition, and the patterning of the first mask may utilize such differences in wetting in forming the first mask.

TECHNICAL FIELD

Methods of utilizing block copolymer to form patterns.

BACKGROUND

A continuing goal of semiconductor processing is to increase integrationdensity. This goal of increasing circuit density permeates throughfabrication of all types of circuitry, including memory, logic andsensors. Significant improvement in integrated circuit density may beachieved by reducing the size of individual structures in layouts inwhich there is a large number of repeating units, such as withintegrated memory. The individual structures of integrated memory may becomprised by memory-storage units. Example memory-storage units are NANDunit cells, dynamic random access (DRAM) unit cells, and cross-pointmemory unit cells.

Photolithography is a conventional method utilized for fabrication ofintegrated components. Photolithography utilizes light to pattern aphotosensitive material. The photolithographically-patternedphotosensitive material may then be utilized as a mask for patterningunderlying materials to form integrated circuit components.

If only photolithography is utilized to pattern integrated circuitcomponents, integrated circuit density cannot increase beyond athreshold dictated by the minimum attainable feature size obtainableutilizing the photolithography. The minimum feature size may be dictatedby, for example, a wavelength utilized during the photolithography.

Several methods have been developed which can be utilized in combinationwith photolithography to push the minimum attainable feature size tosmaller dimensions than may be achieved with photolithography alone.Among such methods is a procedure comprising utilization of a blockcopolymer to form a pattern within photolithographically-patternedfeatures. The pattern created with the block copolymer may be at higherdensity than is achievable with photolithographic patterning, and thusmay be utilized to create higher integrated circuit densities than areachievable with photolithography alone.

Although the utilization of block copolymers shows promise forincreasing integrated circuit density, there are technical obstacles toovercome before block copolymers are adopted for wide-scale use insemiconductor device fabrication.

It would be desirable to develop new methods of forming patterns withblock copolymers which enable repeating patterns to be formed to highdensity. It would be further desirable for such methods to be readilyapplicable for semiconductor device fabrication.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1-5 illustrate a portion of a semiconductor construction atvarious process stages of an example embodiment.

FIGS. 6-8 illustrate the portion of the semiconductor construction ofFIG. 2 at various process stages subsequent to FIG. 2 in accordance withanother example embodiment.

FIGS. 9-14 illustrate a portion of a semiconductor construction atvarious process stages of another example embodiment.

FIG. 15 illustrates a portion of a semiconductor construction at aprocess stage subsequent to that of FIG. 2 in accordance with anotherexample embodiment.

FIG. 16 illustrates a portion of a semiconductor construction at aprocess stage subsequent to that of FIG. 11 in accordance with anotherexample embodiment.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

Some embodiments include methods in which material is provided over asubstrate and patterned into a first masking pattern. Subsequently, thematerial is treated to form repeating segments within the material, andthen one or more of the segments is selectively removed to form a secondmasking pattern superimposed within the first masking pattern. Exampleembodiments are described with reference to FIGS. 1-16.

Referring to FIG. 1, a portion of a semiconductor construction 10 isillustrated. The construction 10 includes a semiconductor substrate 12and a material 18 formed over the substrate.

Substrate 12 comprises a base 14, and a material 16 supported over thebase.

The terms “semiconductive substrate” and “semiconductor substrate” meanany construction comprising semiconductive material, including, but notlimited to, bulk semiconductive materials such as a semiconductive wafer(either alone or in assemblies comprising other materials thereon), andsemiconductive material layers (either alone or in assemblies comprisingother materials). The term “substrate” refers to any supportingstructure, including, but not limited to, the semiconductive substratesdescribed above.

Base 14 may correspond to a semiconductor material, and in someembodiments may correspond to a monocrystalline silicon wafer.

Material 16 represents a material which is to be patterned duringfabrication of integrated circuitry. Material 16 may be an electricallyinsulative material (for instance, may comprise one or more of siliconnitride, silicon dioxide, etc.), an electrically conductive material(for instance, may comprise one or more of various metals,metal-containing compositions, conductively-doped semiconductormaterial, etc.) or a semiconductive material (for instance, silicon,germanium, etc.). Although only the single material 16 is shownsupported by base 14, in some embodiments multiple materials may besupported by the base. For instance, if it is desired to form NAND unitcells over base 14, there may be a plurality of gate materials stackedover the base; with such gate materials ultimately being simultaneouslypatterned to form a plurality of gate constructions supported by thebase. As another example, if it is desired to form cross-point memory,there may be a plurality of materials stacked over base 14; with suchmaterials ultimately being simultaneously patterned to form a pluralityof lines extending across the base. As yet another example, if it isdesired to form DRAM, there may be a plurality of materials stacked overbase 14; with such materials ultimately being simultaneously patternedto form a plurality of wordlines and/or bitlines extending across thebase.

Material 18 is radiation-sensitive so that it may be patterned byphotolithographic methodology, and comprises block copolymer. In someembodiments, material 18 may comprise a blend of block copolymer andconventional photoresist. In other embodiments, material 18 maycomprise, consist essentially of, or consist of a material whichincludes both the self-assembling properties of block copolymers and thephotosensitivity of photoresist materials. Material 18 may have one ormore “leaving groups”, which are either radiation-releasable and/orreleasable after interaction with additional species that areradiation-releasable, (e.g. photo-acids). Such leaving groups may bereferred to as leaving groups that may be released throughradiation-induced cleavage.

Copolymers are polymers derived from two or more different monomericspecies. Block copolymers contain two or more homopolymer subunitslinked by covalent bonds. The union of the homopolymer subunits mayutilize an intermediate non-repeating linkage, known as a junctionblock. The term “block copolymer” may be generic for any heterogeneousmaterial that can micro-phase separate to form domains onsub-lithographic-length scales. Block copolymers may be, for example,organic, organo-metallic, or organo-Si. Block copolymers with twodistinct blocks may be referred to as diblock copolymers. Blockcopolymers may be identified by the number of distinct homopolymersubunits contained therein. For example, block copolymers containingonly two distinct homopolymer subunits may be referred to as diblockcopolymers, and block copolymers containing only three distincthomopolymer subunits may be referred to as triblock copolymers.

Example block copolymers that may be utilized in applications in whichthe copolymer is dispersed in conventional photoresist arepolystyrene-b-poly (2-vinylpyridine) (PS-b-P2VP); polystyrene-b-poly(ethylene-alt-propylene); polystyrene-b-poly(methylmethacrylate)(PS-b-PMMA); polystyrene-block-poly(ethylene oxide) (PS-b-PEO); andpolystyrene-b-poly(dimethyl-siloxane) (PS-b-PDMS). The “b” utilized ineach of the above chemical formulas indicates a block linkage.

Example block copolymers that may be utilized in applications in whichthe copolymer is utilized as a radiation-sensitive compound arecopolymers analogous to PS-b-PMMA, and comprising modified subunits thatcontain leaving groups that may be released through radiation-inducedcleavage; with such molecules being base soluble after cleavage of theleaving groups in some embodiments. The modified subunits may be thepolystyrene subunit alone, the methylmethacrylate subunit alone, or boththe polystyrene subunit and the methylmethacrylate subunit.

If the polystyrene subunit is modified, such modification may utilizepoly{4-[(tert-butoxycarbonyl)oxy]styrene} in place of the polystyrene,with the tert-butoxyl group being a leaving group that may be releasedthrough radiation-induced cleavage; and if the methylmethacrylatesubunit is modified, such modification may utilizecycloolefin-polymethacrylate in place of methylmethacrylate, with thecycloolefin being a group that may be released through radiation-inducedcleavage.

Other example block polymers are PS-b-PS_(modified)-b-PMMA andPS-b-PMMA-b-PMMA_(modified); where PS_(modified) and PMMA_(modified) arederivatives of polystyrene and poly(methylmethacrylate), respectively.

Material 18 may be deposited over material 16 utilizing any suitablemethodology, including, for example, spin-on methodologies. Material 18may be treated with a so-called “soft bake” after deposition of material18. In some embodiments, the soft bake may be at a temperature that isnear or below the glass transition temperature (Tg) of material 18. Insome embodiments, the soft bake may be at a temperature of from about110° C. to about 120° C., while material 18 has a Tg of from about 140°C. to about 150° C. The soft bake may be utilized to remove solvent thatwas present in material 18 as a carrier during deposition of material18.

Material 18 may be photolithographically patterned, and FIG. 2 showsconstruction 10 at a processing stage after photolithographic patterningof material 18. The patterning has formed material 18 into a patternedmask 19. Patterned mask 19 includes a plurality of masking features 20,22 and 24, which are spaced from one another by intervening gaps 26 and28. The patterned mask of FIG. 2 (i.e., the mask formed byphotolithographic patterning of material 18) may be referred to as afirst patterned mask to distinguish it from other masks formed insubsequent processing (discussed below).

The photolithographic patterning of material 18 comprises exposure ofsome regions of material 18 to electromagnetic radiation (i.e. actinicradiation), while leaving other regions unexposed; followed byutilization of a developer solution to remove either the exposed orunexposed regions, and to leave the non-removed regions as the patternedmask.

The exposure of some regions of material 18 to electromagnetic radiationmay be considered to be exposure of material 18 to patternedelectromagnetic radiation. The patterned electromagnetic radiation maybe of any suitable wavelength, and may, for example, be 365 nanometerwavelength radiation, 248 nanometer wavelength radiation, 193 nanometerwavelength radiation, extreme ultraviolet (EUV) radiation, etc.

In some embodiments, material 18 may receive a thermal treatment afterthe exposure to the electromagnetic radiation, and prior to theutilization of the developer. Such thermal treatment may be referred toas a “post exposure bake”, and may be utilized to enhance migration ofchemicals (for instance acid) within chemically-amplified photoresist.The post exposure bake may be conducted at a temperature of less than orequal to a glass temperature of material 18 (with the glass transitiontemperature being a temperature of at least about 100° C. and less thanor equal to about 150° C. in some embodiments); and in some embodimentsmay be conducted at a temperature of from about 90° C. to about 120° C.

In embodiments in which material 18 comprises block copolymer dispersedin conventional photoresist, the conventional photoresist may be achemically-amplified resist. If the addition of the block copolymerinfluences a rate of chemical amplification, the concentration ofamplifying chemical and/or the duration of a post-exposure bake may beadjusted to compensate for such influence. For instance, the chemistryor the concentration of a photoacid generator (PAG) may be adjusted.

In embodiments in which material 18 comprises block copolymer modifiedto have leaving groups that may be released through radiation-inducedcleavage, such block copolymer may be utilized in combination withchemical amplifiers (such as, for example, PAGs). In such embodiments,the duration and temperature of the post-exposure bake and/or photoacidgenerator chemistry, and/or photoacid quench chemistry, may be adjustedto obtain desired amplification of the effect of the electromagneticradiation exposure.

In embodiments in which the block copolymer comprisespoly{4-[(tert-butoxycarbonyl)oxy]styrene} andcycloolefin-polymethacrylate (or similar blocks), the exposure toradiation may convert the subunits of the block copolymer topolyhydroxystyrene (PHOST) and polyacrylic acid (PAA) or similarsubunits that may be developed and selectively removed/left from thesubunits in unexposed regions. In some embodiments, such conversion maybe chemically amplified with a post exposure bake. The specificchemistry described herein is an example chemistry, and otherembodiments may utilize other chemistries to achieve similar results.

The exposure to the electromagnetic radiation, and the post-exposurebake (in embodiments utilizing a post-exposure bake), cause someportions of material 18 to be modified relative to other portions. Thedeveloper mentioned previously is then utilized to selectively removeeither the modified portions, or the unmodified portions. The developermay be a conventional developer suitable for selectively dissolvingeither the modified or unmodified portions, and may, for example,comprise an aqueous solution of tetramethylammonium hydroxide (TMAH). Inembodiments comprising blends of block copolymer and photoresist, theblock copolymer in exposed regions may be “developable” by the action ofa photoacid generator, and/or the developer may be configured forselectively dissolving the block copolymer in exposed regions withoutextracting significant amounts of block copolymer from the unexposedregions.

An upper surface of material 16 is uncovered within gaps 26 and 28. Insome embodiments, the uncovered upper surface of material 16 may becoated, grafted and/or functionalized to change properties of the uppersurface so that it becomes less wettable relative to material 18. Suchcan impede material 18 from accumulating across gaps 26 and 28 insubsequent processing (discussed below). In some embodiments, the amountof material 18, size of gaps 26 and 28, and parameters of the subsequentprocessing may be adjusted so that material 18 does not disperseentirely across gaps 26 and 28 regardless of whether or not the uppersurface of material 16 is treated. It is noted, however, that there mayalternatively be some embodiments in which it is desired for material 18to extend entirely across gaps 26 and 28 after the subsequentprocessing.

Referring to FIG. 3, material 18 is subjected to conditions that induceself-assembly of the block copolymer to form features 32 and 34 from theblock copolymer. The block copolymer may be a diblock copolymer, and insuch embodiments may be generically represented as A-B, where the “A”represents one of the homopolymer subunits, the “B” represents the otherof the homopolymer subunits, and the hyphen represents a covalent bond.A pattern resulting from self-assembly of diblock copolymer may bedesignated by the shorthand A-B:B-A:A-B:B-A; where the hyphen representscovalent interactions, and the colon represents non-covalentinteractions. Thus, features 32 may comprise the A subunits of the blockcopolymer, and features 34 may comprise the B subunits of the blockcopolymer, or vice versa. The features 32 and 34 differ from one anotherrelative to the wetting of air and substrate interfaces, and this leadsto the self-assembly of the features 32 and 34 into the pattern shown inFIG. 3. FIG. 3 illustrates one of many configurations that may resultfrom self-assembly of block copolymer. FIG. 15 shows anotherconfiguration that may result from self-assembly of the block copolymer.

In some embodiments, the features 32 may include other components inaddition to one of the subunits of the block copolymer. For instance, inembodiments in which material 18 (FIG. 2) comprises the block copolymerin a mixture with other substances, the features 32 may include suchother substances as well as including one of the subunits of the blockcopolymer.

In some embodiments, features 32 may be considered to alternate withfeatures 34 along a cross-section through masking blocks 20, 22 and 24;and in such embodiments the features 32 and 34 along such cross-sectionmay be considered to comprise alternating first and second segmentsformed from the block copolymer.

The features 34 may be considered to correspond to a second patternedmask 35 that is formed from the first patterned mask 19. Also, a patternof the features 34 may be referred to as a second pattern. Such secondpattern may be considered to be within the first pattern correspondingto the pattern of features 20, 22 and 24, or to be superimposed on thefirst pattern corresponding to the pattern of features 20, 22 and 24.

FIG. 3 illustrates one of many configurations that may result fromself-assembly of block copolymer. FIG. 15 shows another configurationthat may result from self-assembly of the block copolymer. In theembodiments of FIGS. 3 and 15, features 34 are cylinders extending intoand out of the page relative to the cross-sectional views of thefigures. In other embodiments the features may be lamellae, micelles, orsurface-perpendicular cylinders.

The conditions utilized to induce self-assembly of the copolymer may bethermal conditions, and may utilize a temperature greater than about theglass transition temperature of material 18 (such temperature may befrom greater than 150° C. to less than or equal to about 250° C. in someembodiments). In another embodiment, self-assembly may be induced duringa solvent anneal step, where the material is exposed to the partialpressure of an appropriate solvent vapor.

Referring to FIG. 3, the blocks 20, 22 and 24 of the first patternedmask 19 are shown to have undergone reflow during exposure to theconditions utilized to induce self-assembly of the copolymer. Suchreflow has changed the shape of blocks 20, 22 and 24 so that theindividual blocks have now spread, and become dome-shaped. The spreadingof the blocks has reduced the size of gaps 26 and 28 relative to theinitial size present at the processing stage of FIG. 2. The amount ofspreading of the individual blocks may be influenced by numerousfactors, which may include one or more of the following: the compositionof the blocks, the initial volume of the blocks, the initial shape ofthe blocks, the temperature of a treatment utilized to induceself-assembly of the block copolymer, the duration of such treatment,the type of solvent utilized if a solvent anneal is utilized to inducethe self-assembly, and a drive to minimize a total area of an airinterface. Additionally, the amount of spreading of individual blocksmay be influenced by a composition of the surface of material 16, andspecifically by the contact angle of material 18 relative to surface 16.In some embodiments, at least some of the surface 16 exposed within gaps26 and 28 may be treated to render the surface non-wettable by material18 (FIG. 2) so that the material 18 beads from the surface and does notextend entirely across gaps 26 and 28. Such treatment of surface 16 mayinclude, for example, exposure of the surface to one or more fluoroalkylsilanes and/or silicones; and may be conducted before or after formationof blocks 20, 22 and 24 over surface 16. In another embodiment, the gaps26 and 28 are closed as material 18 (FIG. 2) reflows during theself-assembly anneal to form the second mask 35, and the features 34 arethen formed to be uniformly periodic across the entire surface 16.

The formation of features 34 may be referred to as grapho-epitaxialalignment, and may form the features 34 to a pitch that is substantiallysmaller than a minimum pitch achievable by photolithographic exposure.For instance, features 34 may be formed to a pitch that is less than orequal to one-half of the minimum pitch achievable by thephotolithographic process utilized to form the blocks 20, 22 and 24 ofFIG. 2.

Referring to FIG. 4, most of the features 32 (FIG. 3) are selectivelyremoved relative to features 34, to leave features 34 of patterned mask35 remaining over material 16. Some of the features 32 remain beneathfeatures 34 in the shown embodiment due to anisotropy of the etchutilized to remove features 32. One method of selectively removing theshown portions of features 32 relative to features 34 is to firstselectively modify features 34 relative to features 32 by oxidizing ormetalizing the features 34 (i.e., incorporating oxygen or metal intofeatures 34), and to subsequently remove portions of features 32 byashing with O₂ plasma. If the embodiment of FIG. 15 were utilizedinstead of that of FIG. 3, a punch-through etch may be conducted toremove at least part of the outer skin (which one of the features 34 inthe FIG. 15 embodiment) and thereby expose features 32 for subsequentremoval.

Referring to FIG. 5, the patterned mask 35 may be utilized to fabricatea pattern within material 16. In some embodiments, material 16 may berepresentative of one or more materials utilized for fabrication ofmemory architecture (e.g., NAND, DRAM and/or cross-point memory). Insuch embodiments, the transfer of a pattern into material 16 mayrepresent patterning of one or more materials into structures of memoryarchitecture. In such embodiments, the features 34 may be used to definelocations of integrated circuit components within substrate 12. Forinstance, patterning of material 16 may represent patterning of one ormore gate materials of NAND unit cells; may represent patterning of aplurality of lines of cross-point memory cells; and/or may representpatterning of wordlines and/or bitlines of DRAM.

In some embodiments, features 32 and 34 of FIG. 5 may be removed insubsequent processing; and in other embodiments, features 32 and 34 maybe left to become incorporated into an integrated circuit construction.

FIG. 6 shows construction 10 at a processing stage subsequent to that ofFIG. 2 in accordance with an embodiment in which the self-assembly ofblock copolymer has formed lamella rather than cylinders. Accordingly,the material 18 of FIG. 2 has assembled into alternating segments offeatures 32 and 34. The features 32 and 34 may correspond to the Asubunit of a diblock copolymer, and to the B subunit of the diblockcopolymer, respectively. The construction of FIG. 6 may be induced byany suitable method, including, for example, changing the volumefractions of the A and B subunits relative to the volume fractions thatwould form the construction of FIG. 3. The shown lamellae may form ifthe surfaces of material 16 that are covered by blocks 22, 24 and 26 areneutral relative to wettability by features 32 and 34 (i.e., if features32 and 34 both wet the surfaces to a comparable amount), and if features32 are preferentially formed along an air interface relative to features34.

If composition 18 of FIG. 2 consists of diblock material, then thestructure of FIG. 6 may result from induction of self-assembly of thediblock copolymer. In other words, masking blocks 20, 22 and 24 areconverted into structures in which only repeating segments formed fromthe self-assembly are present after the self-assembly. In otherembodiments, in which material 18 comprises diblock copolymer in amixture with other substances, the blocks 20, 22 and 24 at theprocessing stage of FIG. 6 may comprise other components in addition tothe segments formed from self-assembly of the diblock copolymer.

The blocks 20, 22 and 24 at the processing stage of FIG. 6 areillustrated to be less dome-shaped and less spread than analogous blocksat the processing stage of FIG. 3. Such difference between FIGS. 3 and 6is provided to illustrate that the amount of spreading of blocks 20, 22and 24 that occurs during inducement of self-assembly of block copolymermay be adjusted by adjusting one or more of the parameters discussedabove with reference to FIG.3.

In subsequent processing, one of the two types of features 32 and 34 ofFIG. 6 may be selectively removed relative to the other. If features 34are to be selectively removed, there can be an etch partially intofeatures 32 to expose features 34 for subsequent removal.

FIG. 7 shows construction 10 after the features 32 have been selectivelyremoved relative to the features 34. The remaining features 34 form apatterned mask of upwardly projecting structures over material 16.

FIG. 8 shows construction 10 after the pattern of the patterned mask ofFIG. 7 has been transferred into material 16 with one or more suitableetches.

FIGS. 1-8 illustrate embodiments in which photolithographic processingis utilized to form a first pattern within a photosensitive materialcomprising block copolymer, and then self-assembly of the blockcopolymer is utilized to form a second pattern superimposed on the firstpattern. Other methods besides photolithography may be utilized to formthe first pattern. For instance, FIGS. 9-12 illustrate an exampleprocess in which differences of wettability of a substrate surface areutilized to induce the first pattern in a material comprising blockcopolymer.

Referring to FIG. 9, a portion of a semiconductor construction 50 isillustrated. The construction 50 comprises a substrate 52. In someembodiments, substrate 52 may be a semiconductor substrate. In anexample embodiment, substrate 52 may be a monocrystalline silicon wafer.

Substrate 52 comprises an upper surface 53. In some embodiments, theupper surface 53 may initially consist of silicon or doped silicon. Aplurality of regions 54 are illustrated, with such regions correspondingto segments of upper surface 53 that have been changed in compositionrelative to the remainder of upper surface 53. Such change incomposition will alter wettability of a block copolymer-containingmaterial that is to be subsequently formed over substrate 52. If uppersurface 53 consists of silicon or doped silicon, the treatment of theupper surface may comprise subjecting the upper surface to one or morefluoroalkyl silanes and/or silanols. For instance, regions 54 maycorrespond to portions of the upper surface that have been exposed toperfluoroalkyl silane. Photoresist may be utilized to protect portionsof surface 53 which are not to be altered during the treatment that isutilized to form the alterations that lead to regions 54.

In some embodiments, the regions of upper surface 53 that have not beentreated may be referred to as first regions 51 of the upper surface, andthe treated regions 54 may be referred to as second regions of the uppersurface.

Referring to FIGS. 10 and 11, material 60 is deposited over substrate 52(FIG. 10); and the material then redistributes to not be over theregions 54 of the surface of substrate 52, and to accumulate (or bead)over the regions 51 of the surface (FIG. 11).

Material 60 comprises block copolymer, and in some embodiments consistsof block copolymer dispersed in a carrier solvent. The block copolymermay comprise any suitable block copolymer, and in some embodiments is adiblock copolymer consisting of either polystyrene-block-vinylpyridineor polystyrene-block-ethylene oxide. The block copolymer disperses fromregions 54 along the upper surface of material 52, and beads overregions 51 along such upper surface, due to the differences inwettability of material 60 relative to regions 51 and 54. Specifically,regions 51 may be configured to be wettable by material 60, whileregions 54 are configured to be non-wettable, and such may causematerial 60 to accumulate over regions 51 while dispersing from overregions 54.

The material 60 of FIG. 11 forms a patterned mask 62 having maskingfeatures 64, 66 and 68, which are spaced from one another by gaps 63over the regions 54. The pattern of the masking features 64, 66 and 68of the patterned mask 62 may be referred to as a first pattern.

Material 60 may be deposited by any suitable method, including, forexample, spin-casting.

In some embodiments, the patterned mask 62 may be subjected to alow-temperature bake (i.e., a bake at a temperature of less than aboutthe glass transition temperature of material 60, which may be less thanor equal to 150° C. in some embodiments) to remove carrier solvent; andin other embodiments such bake may be omitted. In some embodiments, thelow-temperature bake may induce the dewetting from regions 54.

Referring to FIG. 12, patterned mask 62 is subjected to conditions whichinduce self-assembly of the block copolymer therein. The self-assemblywithin the block copolymer is shown converting material 60 into features70 and 72. Features 70 are in the form of cylinders extending into andout of the page relative to the cross-sectional view of FIG. 12. Feature72 is over and between the features 70. In some embodiments, features 70may be considered to alternate with features 72 along the across-section through masking blocks 64, 66 and 68; and in suchembodiments the features 70 and 72 along such cross-section may beconsidered to comprise alternating first and second segments formed fromthe block copolymer. In some embodiments, one or both of solventtreatment and thermal treatment (e.g., baking) may induce theself-assembly of FIG. 12 and the dewetting of FIG. 11 simultaneously.

The features 70 may be considered to correspond to a second patternedmask 74 that is formed from the first patterned mask 62. Also, a patternof the features 70 may be referred to as a second pattern, and suchsecond pattern may be considered to be superimposed on the first patterncorresponding to the pattern of features 64, 66 and 68.

Although features 70 are cylinders in the shown embodiment, in otherembodiments the features may have other shapes. For instance, in someembodiments the features may be lamellar. In embodiments in which thefeatures are lamellar, the construction of FIG. 12 may comprisealternating segments of features 70 and 72 analogous to the alternatingsegments 32 and 34 shown in FIG. 6. FIG. 12 illustrates one of manyconfigurations that may result from self-assembly of block copolymer.FIG. 16 shows another configuration that may result from self-assemblyof the block copolymer.

Referring to FIG. 13, most of the features 72 are selectively removedrelative to features 70, to leave features 70 of patterned mask 74remaining over substrate 52. In the shown embodiment, portions of thefeatures 72 remain under the features 70 due to anisotropy of the etchutilized to remove features 72. One method of selectively removing theshown portions of features 72 relative to features 70 is to firstselectively modify features 70 relative to features 72 by oxidizing ormetalizing the features 70 (i.e., incorporating oxygen or metal intofeatures 70), and to subsequently remove portions of features 72 byashing with O₂ plasma.

Referring to FIG. 14, the patterned mask 74 has been utilized tofabricate a pattern within substrate 52. In some embodiments, substrate52 may be utilized for fabrication of memory architecture (e.g., NAND,DRAM and/or cross-point memory). In such embodiments, the transfer of apattern into substrate 52 may represent patterning of one or morematerials into structures of memory architecture. In some embodiments,the features 70 may be used to define locations of integrated circuitcomponents within substrate 52. For instance, patterning of thesubstrate may represent patterning of one or more gate materials of NANDunit cells; may represent patterning of a plurality of lines ofcross-point memory cells; and/or may represent patterning of wordlinesand/or bitlines of DRAM.

In some embodiments, features 70 and/or modified regions 54 may beremoved in subsequent processing; and in other embodiments, features 70and/or modified regions 54 may be left to become incorporated into anintegrated circuit construction.

The embodiments specifically shown are example embodiments, and theinvention includes other embodiments which are not specifically shown.For instance, the example embodiments shown in FIGS. 1-16 induceself-assembly of block copolymer to form masking features that extendhorizontally across a substrate surface (specifically, the features 34of FIG. 4, the features 34 of FIG. 7, and the features 70 of FIG. 13).In other embodiments, not shown, self-assembly of block copolymer mayform structures that extend vertically (i.e., project primarilyupwardly) relative to a substrate surface. Such vertical structures maybe utilized for various applications in semiconductor fabrication,including, for example, fabrication of contact openings to wiring orother electrically conductive structures.

In compliance with the statute, the subject matter disclosed herein hasbeen described in language more or less specific as to structural andmethodical features. It is to be understood, however, that the claimsare not limited to the specific features shown and described, since themeans herein disclosed comprise example embodiments. The claims are thusto be afforded full scope as literally worded, and to be appropriatelyinterpreted in accordance with the doctrine of equivalents.

1. A method of forming a pattern, comprising: depositing a blockcopolymer-comprising composition over a substrate; photolithographicallypatterning the composition to form a first mask from the composition;and after photolithographically patterning the composition, inducingassembly of the block copolymer to form a second mask from the firstmask.
 2. A method of forming a pattern, comprising: depositing aradiation-sensitive composition over a substrate, theradiation-sensitive composition comprising block copolymer containingone or more leaving groups that are released through radiation-inducedcleavage; photolithographically patterning the radiation-sensitivecomposition to form a first patterned mask from the radiation-sensitivecomposition; and after photolithographically patterning theradiation-sensitive composition, inducing assembly of the blockcopolymer to form a second patterned mask within the first patternedmask.
 3. The method of claim 2 wherein the block copolymer is a diblockcopolymer.
 4. The method of claim 2 wherein the radiation-sensitivecomposition comprises the block copolymer dispersed in a photoresist. 5.The method of claim 2 wherein the radiation-sensitive compositionconsists of the block copolymer.
 6. A method of forming a pattern,comprising: depositing a radiation-sensitive composition over asubstrate, the radiation-sensitive composition comprising blockcopolymer containing one or more leaving groups that are releasedthrough radiation-induced cleavage; exposing the radiation-sensitivecomposition to patterned electromagnetic radiation followed by developerto remove a first portion of the radiation-sensitive composition whileleaving a second portion of the radiation-sensitive composition in afirst pattern induced by the patterned electromagnetic radiation;inducing assembly of the block copolymer to form a second pattern fromthe radiation-sensitive composition; and wherein the block copolymercomprises at least one of poly{4-[(tert-butoxycarbonyl)oxy]styrene} andcycloolefin-polymethacrylate.
 7. A method of forming a pattern,comprising: depositing a material over a substrate, the materialcomprising diblock copolymer and being photolithographicallypatternable; photolithographically patterning the material to form afirst pattern; after forming the first pattern, inducing assembly of thediblock copolymer to form alternating first and second segments withinthe patterned material; selectively removing one of the first and secondsegments relative to the other of the first and second segments to forma second pattern superimposed on the first pattern; and utilizing thesecond pattern to define locations of integrated circuit componentswithin the substrate.
 8. The method of 7 wherein the photolithographyincludes: exposure to patterned actinic radiation; thermal treatment ofthe material at a temperature of less than or equal to about a glasstransition temperature of the material after the exposure to the actinicradiation; and exposure to a developer after the thermal treatment. 9.The method of 8 wherein the thermal treatment is a first thermaltreatment, and wherein the inducing assembly of the diblock copolymercomprises a second thermal treatment; said second thermal treatmentbeing at a temperature of greater than about the glass transitiontemperature of the material.
 10. The method of 7 wherein the integratedcircuit components are part of one or more of a DRAM array, a NANDarray, and a cross-point memory array.
 11. A method of forming apattern, comprising: depositing a material over a substrate, thesubstrate having a plurality of first regions and a plurality of secondregions, with the first regions being more wettable to the material thanthe second regions; the material comprising diblock copolymer and beingpatterned into a first pattern by the difference in wettability relativeto the first and second regions of the substrate; after the material ispatterned into the first pattern by the difference in wettabilityrelative to the first and second regions, inducing assembly of thediblock copolymer to form alternating first and second segments withinthe patterned material; selectively removing at least some of one of thefirst and second segments relative to at least some of the other of thefirst and second segments to form a second pattern superimposed on thefirst pattern; and utilizing the second pattern to define locations ofintegrated circuit components within the substrate.
 12. The method of 11wherein the diblock copolymer is PS-b-P2VP, PS-b-PEO, or PS-b-PDMS. 13.The method of 12 wherein said first regions consist of silicon or dopedsilicon, and wherein said second regions comprise silicon-containingregions that have been treated with one or more fluoroalkyl silanes,and/or with one or more silicones, and/or with other dewetting agents.14. The method of 13 wherein the second regions are formed by treatingportions of the substrate with one or more fluoroalkyl silanes and/orwith one or more silicones.
 15. The method of 11 wherein the integratedcircuit components are part of one or more of a DRAM array, a NANDarray, and a cross-point memory array.